Art of brewing beer.



L. NATHAN.

ART OF BREWING BEER.

APPLICATION FILED nEc.26. I913.

Patented Oct. 1, 1918,

WITNESSES I/IIVEIVTOR ART or nnnwmo BEER.

aasaaso.

Specification of Letters Iiatent.

Patented Unit. 11, 1918.

Application filed December 26, 1913. Serial No. 808,787.

To all whom it may concern.-

Be it known that I, IIEOPOLD NATHAN, a citizen of the German Empire, anda resident of Zurich, Switzerland, have invented a new and usefulImprovement in the Art of Brewing Beer, of which the following is aspecification.

This invention relates to an improved process for preparing beer and hasfor one of its objects the preparation of a beer which is substantiallyfree from free oxygen or air.

I have found that with certain kinds of beer especially those rich inthe extract of hops, the amount of air necessary to permit properfermentation is a great deal less even than I believed it to be when Ifiled my application which became United States Letters Patent No.915,791 of March 23, 1909.

My invention may be carried out in various apparatus and appliances forexample as shown in the accompanying drawing representing a sectionalelevation thereof as described in the Patent No. 899,756 issued to HansBolze and myself. The vessel 5 has a cover 6 for closing ithermetically, and the inner walls should be devoid of projections tofacilitate cleaning,,.and should be enameled so as to protect the wortand the beer against the injurious influence of contact with metal. Thecover has a stuffing box 7 and a bracket, 8 in which is journaled thevertical shaft 9 driven by bevel gearing l0 and carrying at its lowerend the spindle 11 provided with the stirrer 12; shown consists of fourblades or wings inclined relatively to the axis of rotation. At thebottom of the vessel 5 is located a supply pipe 13, and the vessel5 isfurther surrounded by a jacket 14 through which a heating medium or acooling medium may be circulated. The supply pipe 13 is connected withthe surrounding air through the medium of air filter 15 of any suitableconstruction (a box filled with cotton batting will do), the connectionbeing controlled by a valve 16. The pipe, 13, also has anotherconnection, controlled by a valve 17 and leading to a vessel 18 adaptedto contain the yeast used for producing fermentation. The air or theyeast may be conveyed through the supply pipe 13 either by pressure,or'by suction, as by means of a vacuum pump 19 connected with the upperpart of the vessel 5 or with the cover 6 thereof.

Apparently, so far as my present researches have gone, the amount of airnecesthe latter as sary for permitting proper fermentation need not bemore than that which the yeast takes up upon suitable exposure to theatmosphere.

The presence of air in the finished beer, even in relatively smallquantities, may

have, and often does have, a deleterious efl'ect upon the beer, sucheffect becoming more pronounced the longer the beer is stored in thebarrel.

The carbonic acid gas will be dissolved in greater quantity than theoxygen.

Based upon the above facts I have developed a process for brewing beeras free as possible from air, so that not only the finished beercontains substantially no air in solution, but air is excluded, as muchas pos sible, during the fermentation process itself, only so much airbeing admitted as is necessary to permit the yeast cells to grow, and toconvert a suitable amount of sugar into alcohol and carbon dioxid.Incidentally I thus control, to a large degree, the extent of growth ofthe yeast, and prevent. excessive yeast generation, so as not to deprivethe beer of an excessive quantity of useful constituents. Instead oflimiting my growth of yeast to about three or four times its originalamount, as described in my above mentioned Letters Patent, I find that Imay reduce the growth of yeast to about twice its original amount andthus obtain a better product.

The process which I have devised is applicable to every process ofbrewing beer, but is of especial value in the rapid process of brewingbeer which is more particularly set forth in the above mentioned LettersPatent, and also in Letters Patent to myself and Hans Bolze, No.899,756, September 29, 1908. In these patents I have described,generally speaking, a process which involves the stirring of thefermenting wort, in order to expedite the growth of yeast, such stirringbeing preferably done by means of a current of carbonic acid gas.

The hot wort contains practically no air, that is to say, no freeoxygen. When the wort is allowed to cool it absorbs air, which ispartlytaken up into solution, and the oxygen of which is partly chemicallycombined with the wort. It is necessary to permit some air to enter thewort as the chemical combination of oxygen with wort is necessary inorder to produce the proper flavor. This chemical combination can,however, not be effected without at the same time introducing surplusair into solution, which air should be removed as far as possible fromthe Wort before the yeast begins to be active therein.

By removing the air in solution from the wort, and then adding justenough air to permit the yeast to grow to the desired extent, I obtain afinished beer substantially free from dissolved air. I may remove theair from the wort by the following methods:

(1) The hot wort is run into a sterilized vessel and allowed to cooltherein as described in my Patent No. 915,7 91. Instead of waiting untilthe temperature has fallen to about 50 (1., as described in such patent,and then shutting off the air supply and introducing carbonic acid gasto take care of the partial vacuum, I shut off such air supply andcommence the introduction of carbonic acid gas long before thetemperature has fallen to that degree, and as nearly as possible at atime when enough air has been absorbed to produce the requisite amountoxygen compounds, required for the proper flavor of the finished beer.For example, I may stop when the temperature has fallen to about 75 0.,that is to say, at a time when a great deal less air has been absorbedby the cooling Wort than is absorbed in the process described in saidLetters Patent. This step is not essential to my process as I may removeexcess of air by the carbonic acid gas treatment, hereinafter to bedescribed, but is of advantage inasmuch as it makes it unnecessary tocarry on such carbonic acid gas treatment for any great length of time.

When the wort has been cooled I may pass carbonic acid gas through thesame, such carbonic acid gas, upon the principle above described, beingabsorbed by the wort, and simultaneously causing the air held insolution to leave the wort.

(2) While the above is my preferred method, I may also remove the air insolution by placing the wort in the fermenting tank and placing yeast inthe bottom of such tank. The carbonic acid gas produced by thefermentation of the yeast will rise in the Wort and be partly dissolvedthereby, in greater quantity than the oxygen wort in solution. Incarrying out this specific process it may be necessary to use suitablemeans to keep the yeast in the lower part of the fermenting tank, forinstance by cooling the lower part of the fermenting vessel. Inconsidering this specific process the wort must be considered as dividedinto two portions, the lower portion in which fermentation is actuallytaking place, and the upper portion in which no fermentation as yettakes place, but which is subjected to a deaeration process by means ofthe gas escaping from the first portion. This second por- 66 tion, ofcourse, eventually must be considered as being incorporated in the firstportion when the fermentation becomes general throughout the mass ofwort in the tank.

In practice I combine methods (1) and (2), employing the latter toassist in removing such free oxygen as has not been removed by theformer.

After the wort has been de-aerated, as above described, the yeast may beintroduced so that the fermentation process may begin. Preferably, asalready stated, the yeast has already been aerated so as to have takenup a suflicient amount of air to'enable it to grow to the desiredextent. Of course, the air and the yeast may be introduced into the wortseparately.

In my earlier patents I have described a process for bringing aboutrapid fermentation, which process may be carried on by a stirring of thewort,'preferably by means of a current of carbonic acid gas, the use ofsuch gas as a stirring means having the particular advantage that itcarries away the immature bouquets formed during fermentation, withoutgiving a flat taste to the beer. If this process is employed in carryingout my present process, I take care to use carbonic acid gas only afterthe same has bee'nfreed, as far as possible from air, or free oxygen, soas not to introduce quantities of air into the fermenting wort any morethan absolutely necessary. Whether or not it is desired to carry on sucholder process in connection with my present process, it is of advantagein my present process to pass a current of carbonic acid gas through thefermenting wort in order to remove, as far as possible, solution in thewort. It is obvious that if, during the fermentation process, a streamof carbonic acid gas is introduced into the wort from the outside of thetank, less care will have to be used in the removal of air from the wortbefore the fermentation process be gins. In fact, it is possible in manycases that time may be saved by not removing the air as thoroughly aspossiblebefore the commencement of fermentation, but to remove the airduring the process of fermentation. Thus my process has particular valuewhen combined with the process disclosed in my former patents. Ofcourse, such added carbonic acid gas is in part absorbed by the wort andremains in the finished beer.

The carbonic acid gas which is passed through the wort should, ofcourse, as already stated, he as free from air as possible. If thecarbonic acid gas resulting from the fermentation is used for thispurpose it is necessary to remove not only the air, but the essentialoils, esters, etc., which form the immature bouquets created by thefermentation. It is obviously advisable to collect the carbonic acid gaswhich has passed through the wort and to purify the same so that it anyair which may still be left in lid in as finely divided maaaeo sist of amixture of some of the carbonic acid gas created by fermentation andsome of the carbonic acid gas which has been introduced into the wortfrom the outside of the tank, and this mixture will contain some air andsome of the immature bouquets. In order that this carbonic acid gas maybe used over again, I remove the oxygen from the same by one of thefollowing methods:

(a) I pass the gas through a glowing contact substance such as platinumsponge or palladium asbestos and burn up the oxygen by blowing inhydrogen, thus forming water.

(6) The gas can be passed through iron sulfate FeSO which removes theoxygen.

(0) The gas may be passed over glowing copper shavings.

(d) The spent yeast taken from the fermenting tank is removed to anothervessel under exclusion of air, and the gas is passed, a state aspossible, through the yeast. It will be found that the amount of spentyeast obtained in this process is usually quite sufiicient to absbrb theamount of oxygen to a degree and amount suitable for this process.

Any other suitable method may, be used for this purpose. bouquets shouldalso be removed by suitable means. This may be done by various methodsalready known, or by a method devised by me which forms the subjectmatter of a separate application. I have found, also,

of course,

that these immature bouquets are removed by passing the gas over glowingcopper shavings, so that when process (0) is used, both the oxygen andthe immature bouquets may simultaneously be removed. Some of theimmature bouquets are also removed simultaneously with the oxygen whenspent yeast is used according to the above described method (d).

It may be found very difficult to remove absolutely all the oxygen fromthe carbonic acid gas by any of the above mentioned methods, but it isof course obvious that the more the carbonic acid gas is free from airor oxygen, the more nearly the perfect conditions contemplated by myprocess are obtained.

Care should,.of course, be taken that during the process of removing airfrom carbonic acid gas no air should accidentally be re-introduced. Inother words, the various receptacles,cleaning apparatus, pipes, pumps,etc, should be absolutely air tight. It is of advantage not to permitthe gas to come into contact with the water seal in the gasometer, butto cover such seal with a suitable liquid such as paraflin oil orVaseline.

It is also advisable not to collect the gas from the upper surface ofthe wort at the The immature beginning of the process, but to permitsuch gas to blow off into the atmosphere until the air in the upperportion of the fermenting tank has had an opportunity to escape. Suitable indicating devicesmay be applied to the top of the closedfermentation tank, which enable the brew" master to ascertain when asubstantial quantity of air no longer" passes off with the gas. it isadvisable also to provide suitable air indicating devices at variousparts of the purifying and storing apparatus, so that any leakage may beimmediately discovered and checked.

By the process above described a beer is produced substantially freefrom dissolved air (oxygen). It is, however, commercially impracticableto produce carbonic acid gas absolutely free from air so that eventhough the process be carried on under conditions as commerciallyperfect as may be, a small quantity of air may still be found in thebeer. This small quantity may be removed in the following manner:

The beer, preferably while still in the fermenting tank, is subjected toan additional pressure, preferably of carbonic acid gas, and is keptunder such pressure for a short time to permit yeast to settle. Thepressure may for instance be increased to 1.6 atmospliere or even higheras against a usual pressure of 1.4 atmosphere. The pressure is thenremoved gradually by permitting the gas to blow off, and the yeast thenrises in the beer. The yeast absorbs the free oxygen remaining in thebeer and thereafter gradually settles to the bottom, so that the beeritself is free from free oxygen.

It is, of course, to be understood that my process may be varied withincertain limits y those skilled in the art and that the same may becarried on in a less perfect manner and still embody my invention asoutlined in the appended claims.

When I speak in my claims of cooled wort I mean a wort in which thefermentation has not been completed.

I claim: a

1. In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort.

2. In the art of brewing plfivement beer, the imwhich consists insubstantially complete removal of free oxygen from the cooled wort bymeans of substantially pure carbonic acid gas.

3. In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort byintroducing into the fermenting vessel carbonic acid gas, collecting theescaping fermentation gases and re-introducing the same into the wortwhile the fermentation is still going on.

4:. In the art of brewing beer, the improvement which consists insubstantially com- Y of the free oxygen from the cool wort beforefermentation has begun in such wort, and then fermenting the wortsubstantially as described.

6. In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort,before fermentation is'beg'un and then fermenting the wort by means ofaerated yeast.

7 In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort,before fermentation is begun and then fermenting the wort by means ofaerated yeast and then removing any remaining free oxygen from thefinished beer.

8. In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort,before fermentation is begun, and then fermenting the wort by means ofaerated yeast, and then removing any remaining free oxygen from thefinished beer by subjecting the beer in the presence of yeast tosuitable added pressure of a suitable gas, and then gradually releasingsuch pressure.

9. In the art of brewing beer, provement which consists in substantiallycomplete removal of free oxygen from the cooled wort, fermenting thewort by means of aerated yeast, and then removing any remaining freeoxygen from the finished beer by subjecting the beer in the presence ofyeast to a suitable pressure of a suitable gas, and gradually removingsuch pressure.

the im- 10. In the art of brewin beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort, thenfermenting said Wort by means of aerated yeast and simultaneouslypassing through the wort a current of carbonic acidgas, as free aspossible from free oxygen.

11. In the art of brewing beer, the improvement which consists insubstantially complete removal of free oxygen from the cooled wort, thenfermenting said wort by means of aerated yeast and simultaneouslypassing a current of carbonic acid gas, as free as possible from freeoxygen, through the wort, collecting the carbonic acid gas from thesurface of the wort, and then reintroducing the said carbonic acid gassuitably purified into the wort, while the formentation is still goingon.

12. In the art of brewing beer, the improvement which consists infermenting the 'wort and then passing through such wort,

during a suitable length of time, a current of carbonic acid gas fromwhich oxygen has been removed, as much as possible, so that carbonicacid gas enters the wort, and at the same time carbonic acid gas, mixedwith the raw bouquets and air which it has taken up from the liquid,leaves the wort whereby the substantially complete removal of the freeair in the wort is accomplished.

13. In the art of brewing beer, the improvement which consists insubstantially complete removal of air from the finished beer bysubjecting such beer in the presence of yeast to a suitable pressure ofa suitable gas, and gradually removing such pressure.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing wltnesses.

LEOPOLD NATHAN.

Witnesses LOUIS ALEXANDER, JOHN A. FERGUSON.

